Tag Archives: feline infectious peritonitis

Recently a reader of this blog asked me to discuss FIP (Feline Infectious Peritonitis). I am happy to oblige and appreciate the suggestion. If you have topics you would like to learn more about, please let me know in your comments.

(FIP) is a deadly virus that affects mostly young cats and kittens. The FIP virus doesn’t act much like any other virus common to pets. Affected cats don’t survive the infection, although they can linger with symptoms for some time. Unfortunately, there currently are no vaccines that protect against this virus, and there is no exact way to diagnose the infection while the cat is still alive. FIP remains a diagnosis of suspicion until confirmed after death with a necropsy. The cat must be the right age, coming from the right background, and with the right symptoms to be considered possibly infected. It is definitely a frustrating disease for veterinarians to diagnose and for pet owner’s to experience.

FIP is a form of the very common Feline Corona Virus. Almost every kitten is exposed to Corona Virus soon after birth. Corona Virus lives in the GI (gastrointestinal tract) of cats, usually without symptoms and is spread by cat feces. A few cats will have symptoms of mild diarrhea or sneezing, but most cats show no symptoms of Corona Virus at all. Because it is such a common virus, testing a cat for antibodies to corona virus does not verify a diagnosis FIP. Having a blood titer that is positive for Corona Virus simply means that a cat was previously exposed to Corona Virus. A higher titer doesn’t mean a cat
has FIP. It just means the cat might have an active or recent infection of Corona Virus.

For a few cats, the normally mild form of Corona Virus seems to mutate to the deadlier FIP. For these unlucky cats, their own immune system carries the disease throughout their bodies. The virus then affects internal organs in one of two ways. In the “wet” form of the disease, the cat’s chest and/or abdomen begins to slowly fill with a sticky, yellow, fluid. By the time this becomes noticeable, the cat already has difficulty breathing, eating, or moving. Veterinarians can temporarily drain the fluid from body cavities, and testing the fluid can help support a diagnosis of FIP. In the “dry” form of the disease, there are no outward symptoms. The cat slowly deteriorates, and blood work shows multiple organ failures. Biopsies can support the diagnosis. Sadly, FIP is almost always fatal.

Feline Corona Virus seems more likely to mutate to FIP in cats exposed to large numbers of other cats. FIP is more common to cats that once lived in a colony, rescue, shelter, or other facility where many cats mingled. And, research also seems to point to a common genetic link among the affected cats. Only those cats with a genetic susceptibility to the virus that are also exposed to the form of the virus that is more likely to mutate, develop FIP. It happens to a few unlucky cats every year.

For now, there is no way to predict which cats will be affected. The best a pet owner can do to prevent the disease is keep your cat well fed, well vaccinated, and away from other cats. If you must bring a new cat into the home, keep the new cat isolated from your other cats until your veterinarian gives you the OK to let them mingle. FIP isn’t the only disease that cats freely share. So a short quarantine time can prevent many problems when introducing a new cat to the household.

Veterinary scientists are busy working on better diagnostics, treatments, and preventions. Fortunately, FIP is still a rather rare infection. But those unlucky few cat owners who experience the disease are forever scarred.

So who is afraid of FIP? I am. I hate to diagnose it, and I hate that I can’t prevent it.